held in Tokyo, Japan, 23-26 June 1980
International Association for Hydrogen Energy
Organizing Committee of the 3rd World Hydrogen
IN COOPERATION WITH:
Hydrogen Energy Research Laboratories
Yokohama National University
Clean Energy Research Institute
University of Miami
Coral Gables, Florida, U.S.A.
OXFORD • NEW YORK • TORONTO - SYDNEY • PARIS • FRANKFURT
An integrated plan for hydrogen production and distribution within a balanced energy budget is outlined. Primary energy source is the sun, concentrated in earth orbit by satellite and beamed to selected planetside marine locations for hydrogen production from sea water. Primary distribution via already existent natural gas pipeline networks upgraded for hydrogen transmission is augmented by local network extensions and by surface marine transport using modified LNG carriers. The economic, social and environmental impact of this integrated approach is examined in its relationship to continued reliance upon fossil fuel and expanded use of nuclear fission, to increasing reliance upon so-called alternative energy sources, and to the forthcoming nuclear fusion option.
Solar Power Satellite; Satellite Power System; SPS; Microwave power transmission; Laser power transmission; Hydrogen economy; Balanced energy budget; Energy socio-economics; Environment; Marine rectenna.
We are faced with a world-wide energy crisis which has touched most of our lives. The price of heating fuel has spiraled upward so much that the U.S. Government has found it necessary to assist financially disadvantaged families in paying their fuel bills this winter. Lines are forming at gasoline stations across America to purchase automotive fuel whose price has increased over one hundred per cent during the last year.
Led by America, Europe and Japan, the world is moving
towards a predominately electric economy. The accelerating pace of this move is
illustrated in Fig. I. This move is fostering a world-wide increase in electric
generating capacity, placing additional demands on the already severely limited
natural gas and oil supplies. Only a decade ago, nuclear fission seemed the answer
to the world’s diminishing fuel supplies. But production delays in Europe and
America and referendum cancellations in Europe and elsewhere have severely
limited application of the nuclear option, so that today, instead of supplying
40 to 50 per cent of the world electric demand, nuclear power barely supplies
10 per cent of the electrical power requirements of just the industrialized
nations. Governments, private firms and individuals have attacked this problem
from many angles. Wherever the sun shines regularly, solar
power is being pursued with the high technology of silicone cells and sun
tracking concentrators and with the low technology of passive roof collectors
and water storage systems. Americans are extracting geothermal energy from
water for direct use and to distill ethanol, and Germans and Americans are
extracting geothermal energy from hot rocks for the generation of electricity
(U.S. DOE, 1979). A national effort is underway in America to produce ethanol
for mixing with gasoline to expand the available automotive fuel supply. In
Europe and America, significant improvements are being made in the extraction
of liquid and gaseous fuels from coal. Fission reactors are becoming safer and
more efficient. Breeder reactor systems are advancing, and the nuclear waste
disposal problem is being attacked from all sides. National laboratories around
the world are inching closer to a sustained nuclear fusion reaction, and the
availability of this option now seems on the horizon.
Fig. 1. Accelerating trend toward an all electric economy in the U.S.
In spite of all these efforts, the overall impact on the worldwide energy situation is surprisingly small. For example: In the United States, homes consume approximately 25 per cent of the energy produced. Hot water production in homes uses about one third of that. It has been estimated (Davis, 1979) that current solar technology could routinely supply 50 per cent of domestic hot water needs. It therefore follows that if every home in America were routinely to use solar energy for 50 per cent of hot water needs, the savings to the U.S. energy budget would be a scant four per cent. On the likely assumption that American use of hot water is four to five times that of the world average, the world-wide impact of this use for solar energy is almost negligible.
The U.S. Department of Energy (1979a) reports that “employing advance available technology, optimized for energy and cost savings . . . ethanol could be produced for under 26¢ per liter (1979 dollars) . . . in a plant with a 189 million liter per year capacity.” This seems relatively inexpensive until one looks at the underlying problems.
Feedstock cost and energy input cost are-the two major costs involved in the production of ethanol. A common feedstock is corn. Cost of corn in the U.S. during Summer 1979 was 7¢ per liter. Since a liter of corn will produce about .27 liters of ethanol, it costs about 26¢ per liter of ethanol for the feedstock (U.S. DOE, 1979a). Normal distillation requires relatively large quantities of heat from fossil or other primary fuel sources. The only advantage in using fossil fuels lies in converting low energy fuel into the more energy concentrated ethanol. There must be a net energy gain sufficiently large to offset both energy consumed during ethanol production and the high feedstock cost. Two approaches show promise. One is using waste products (such as garbage) for feedstock and waste heat (from smelters, power generation, etc.) for production; the second uses untapped geothermal and solar heat sources. However, the U.S. Department of Energy reports (1979a) that using all food processing waste materials, putting all existing grain land into productive crop use, converting all sugar surpluses and 50 per cent of fermentable municipal solid waste into ethanol would result in a U.S. capacity to produce 17.8 x 10 liters of ethanol per year which is about four per cent of the U.S. 1979 gasoline consumption or about two per cent of the total U.S. energy consumption.
The bottom line of this analysis and the springboard for this report is that today in America if solar energy were universally applied in its most economically viable form, and if every available means were used to produce ethanol, discounting the energy required to generate these results, there would be at most a six per cent energy savings over 1979 levels. What is clearly needed is an integrated approach to energy production which has an across-the-board impact on the energy scene and which retains current attitudes about use of renewable resources and environmental impact considerations.
It is not the purpose of this paper to argue the desirability of a hydrogen economy. Gregory (1973) built a strong case for a hydrogen economy almost a decade ago, and Marchetti (1979) eloquently summarized its advantages during his address at the Second World Hydrogen Energy Conference. What follows is an integrated plan for hydrogen production and distribution within a balanced energy budget. The plan must necessarily be presented in outline form, first because the subject detail would be voluminous, and secondly because some parts of this proposal exist only in the author’s mind and have not been developed beyond the outline stage. Marchetti (1979) argued that the implementation of this economy is a one-hundred year task. Keep this in mind throughout this presentation. The full impact of what follows cannot be felt much before the year 2020 and will not be felt until the world supply of natural gas and oil falls so low that implementation of this or a similar plan becomes a necessity.
The ultimate concept presented here is illustrated in Fig. 2. Sunlight is concentrated in geostationary orbit and beamed to Earth as concentrated laser energy. The receiving sites are marine locations where the incoming energy is used to split sea water into its constituent components, hydrogen and oxygen. The hydrogen is pressurized and passed directly into a pipeline network or liquefied and loaded into tankers for shipment to other pipeline network terminals. These pipeline networks would incorporate facilities for storing hydrogen in either gaseous or liquid form. The hydrogen would then be distributed as it is needed to energy consumers for use either as a direct heating fuel, as a raw material for various chemical processes, or as a source of energy for the local generation of electricity.
Fig. 2 The Hydrogen Energy Economy
This concept differs significantly from current Satellite Power System proposals. These proposals are based upon the SPS Reference System developed by the U.S. Department of Energy (DOE) and the National Aeronautics and Space Administration (NASA). This system combines the results of independent studies conducted for the DOE by the Johnson and Marshall Space Flight Centers. In brief, it features a 10.4 km x 5.3 km x 500 m satellite with a planar array of photovoltaic cells. A one km diameter antenna at one end of the satellite transmits microwave energy to Earth. On Earth, a 10 km x 13 km elliptical receiving rectifying antenna (rectenna) converts the microwaves into direct current which is then distributed along conventional grids. The main characteristics for this reference system are summarized in Table I.
TABLE 1 — Reference Characteristics for the SPS
Source: U.S. DOE (1978b); Glaser and colleagues (1979).
The system proposed here differs from the SPS Reference System in three fundamental ways:
a. Energy is transmitted to Earth as a concentrated laser instead of microwave energy.
b. The rectenna is marine based rather than shore based.
c. Received power is converted into hydrogen for pipeline distribution rather than direct current for grid distribution.
These differences will be looked at in detail later. The overall socio-economic and environmental impact of a Satellite Power System has been studied in depth by the DOE and by NASA (Bachrach, 1978; Baldwin and colleagues, 1978; Bloomquist and colleagues, 1979; Kurolff, 1978; Kotin, 1978; Newsom, 1978; U.S. DOE, 1978b; Vajk, 1978), and has been addressed by numerous independent researchers during the last few years (Collins, 1979; Franklin and Rudge, 1978; Glaser, 19780, 1978b; Glaser and colleagues, 1979; Halverson and colleagues, 1978; Ruppe, 1977; Trello and Reinhartz, 1979; Woodcock, 19780). What follows is an outline of their findings with an emphasis on the economic advantages of the Solar Power Satellite over other primary energy systems. How these findings are impacted by the proposal in this paper will then be addressed with special attention being paid to the socioeconomic and environmental advantages offered by this proposal.
TABLE 2 — Power System Economics
Source: Nansen and Johnson, 1979.
The economics of the Solar Power Satellite can best be understood in its relationship to more conventional power systems. Nansen and Johnson (1979) calculate that the total cost of a 5,000 MW SPS will fall between 7.8 and 17.9 x 109 of 1979 U.S. dollars. This averages to about $2, similar 340 per KW. The current cost of a 1,000 MW coal plant is about $1,000 per KW and of a size nuclear plant $1,300 per KW. For a plant going on line in the year 2000, taking into consideration yearly cost escalation, plant factor, average capitalized cost, fuel cost, and operating and maintenance costs, and assuming an average 40-year plant life, the total cost per KWh for the coal and nuclear plants is 5.1¢, and that for SPS only 3.3¢. The major differences lie in cost escalation which is less for SPS primarily because it can be built faster than the other plants, and in fuel, and operation and maintenance costs. There is, of course, no fuel cost for SPS, and the system is essentially maintenance free. Many experts on SPS are convinced that the satellite may last 75 to 150 years instead of the 40 assumed in the above example. Assuming a 100-year basis instead of 40, and refiguring the capitalized costs, fuel costs, and operating and maintenance costs, the total cost per KWh for a coal plant rises to 7.3¢, for nuclear to 7.0¢ and for SPS falls to 2.6¢. The primary reasons for this are that for coal and nuclear systems two and one half plants will have been amortized and fuel costs will have escalated, whereas the satellite will have lasted the entire period, and it has no fuel costs. See Table 2. There are further considerations. What will be the annual plant revenue requirements, and what will power cost in the future? Nansen and Johnson (1979) have assumed a modest three per cent inflation rate and estimate that a coal plant will require over 10 times the annual revenue of a SPS system after 30 years. The cost of this power will rise to almost 70¢ per KWh for coal and will fall to under 3¢ per KWh for SPS by the year 2040. When looked at over 100-year period, the SPS costs far less than comparable coal plants, decreasing to less than five per cent of the coal plant costs by the eightieth year and continuing lower. See Fig. 3. The long-term cost for nuclear generation would be even higher, because like SPS, it has a very high construction cost, but like coal it also has an increasingly more expensive fuel cost.
Fig. 3. The future cost of power—coal verses SPS.
SPS societal assessment preliminary findings (Bloomquist and colleagues, 1979) highlight the. following important issues: siting, centralization, government involvement, finance and management, international agreements, and public acceptance. These issues stand out because of their high degree of interaction. Siting and centralization are intimately related, although their interrelationship will differ from that established in the original assessment because of the marine location for the rectennas mandated by the proposal presented here. Government involvement is pervasive in all areas of decision making and will be here. Finance and management of the SPS Program, whether private, government, or some combination of both, will be dictated by what is forthcoming from all levels of national and international government. Operations in space are governed by international treaties, and principles of international law, and current proposals before member States of the United Nations may have far-reaching consequences. These proposals seem to shut the door on the private enterprise option for space activities and it is doubtful whether a program like SPS could be brought to term without the strong impetus of profit motivation. Public acceptance is required to obtain favorable outcomes to the other concerns.
Institutions impacted by SPS are those which will regulate, finance and manage it. There is a growing trend in the United States towards a decentralized energy policy. This can create a problem for SPS, and it is difficult at this time to assess the adequacy of existing institutions to deal with the unique features of SPS. What is clear is that within the frame work of the U.S. DOE/NASA Reference System, the SPS is a centralized power source and as such will require regional coordination of power plant regulation.
The financial attractiveness of a project depends on its reward-to-expected-risk ratio. For the SPS there appear to be three major categories of risk: disasters, international repercussions and technological costs. Each of these presents a large unknown. The high implementation cost of the SPS discussed earlier, coupled with this high risk, tends to discourage unilateral private sector financing. Two basic approaches appear possible. The first involves a joint-venture partnership between government and the private sector. The public interest would be assured under the arrangement by regulation of prices and profits and by government license of the technology. Such a model is compatible with public sector international organization involvement. The other approach is compatible with international private sector involvement. It includes two separate models. The first is a staging company model supported by stock sales, resultant investment income, patents, etc. The second is a “universal capitalism” model patterned after Employee Stock Ownership Plans but not restricted to employees. In either case, the research and development phase would be funded by government “Space Bonds,” to ease the initial investment burden on the private sector and to give the public a sense of participation in the SPS Program.
Just how the government and private sectors would interface, what would be regulated, grid electricity pricing policy, financing schemes—all these require clarification.
Because of the international nature of the world-wide energy problem, and because of the inherent nature of the SPS solution to this problem, an international organization is strongly indicated for its development and commercialization. Bloomquist and colleagues (1979) identify four prospective international organizational structure models for the SPS. These are:
a. A public/private corporation akin to COMSAT, which would evolve into an international corporation akin to INTELSAT.
b. An international organization in which the U.S. would retain substantial control.
c. A quasi-governmental agency like the American TVA.
d. A multi-national, private consortium.
No matter which structure is used, successful management of the organization is a function of the ability to relate to the external and internal environment at each stage of program development. Internally the environment could be handled by changing the organizational structure and management objectives with each program stage. During the research and development stage, the program would have a scientific orientation and would be appropriately managed. With full implementation of the system, orientation would be towards production, and management structure would so orient itself. COMSAT/INTELSAT is a good organizational model for the handling of external relationships. COMSAT, the largest shareholder within INTELSAT, provides operational and technical services under a management contract. Voting power is on the basis of financial participation. Any SPS organization must be responsive to national energy needs, politically feasible, cost-effective, and conductive to international cooperation and acceptability.
An internationally acceptable SPS will require extensive treaty provisions. There are three existing international organizations most directly concerned with SPS. They are:
a. U.N. Committee on the Peaceful Uses of Outer Space.
b. International Telecommunications Union.
c. Committee on Space Research of the International Council of Scientific Unions.
There are three existing treaties applicable to SPS and one pending ratification by U.N. member States:
a. 1967 Treaty on Principles governing the activities of States in the Exploration and Use of Outer Space, including the Moon and other Celestial Bodies (U.N.).
b. 1972 Convention on International Liability and Damage Caused by Space Objects (U.N.).
c. 1973 Telecommunications Convention and Final Protocol Treaty.
d. Agreement Governing the Activities of States on the Moon and Other Celestial Bodies (U.N.) (Pending ratification).
The 1967 Principles Treaty considers the space environment open to all who can use it. Since the radio frequency spectrum and geostationary orbit are considered to fall within the “province of mankind” pursuant to this treaty, and since space and its environs are considered part of the “common heritage of mankind,” the question is raised as to who should benefit from the SPS resource.
International law has not yet established microwave exposure standards; however, the 1972 Liability Convention clearly holds a launching State liable for harm produced by microwave radiation emanating from a space object in geostationary orbit. International law also prohibits generating adverse changes in the environment. There is a present lack of knowledge about the health and environmental effects of microwave radiation. This must be addressed internationally by any organization intending to operate an SPS.
The International Telecommunications Union (ITU) is governed by the 1973 Convention and Final Protocol. Under this and previous conventions, radio and microwave frequencies are allocated by ITU, and ITU is also responsible for preventing broadcast interference. Since the SPS has a power transmission function, there is a question of ITU jurisdiction which must be resolved internationally.
The agreement currently before U.N. member States, known as the “Moon Treaty,” may have far-reaching consequences with respect to the SPS. In an attempt to put teeth into arms control agreements, it would allow search without a warrant of any structure in space or on any celestial body other than Earth. In an attempt to protect, developing nations’ share of space resources, it would set up an international regime empowered to create an OPEC-like monopoly over space resources, permanently removing them from private sector exploitation. This would drastically reduce the options available for SPS implementation, and would delay that implementation for years. But the Moon Treaty has not been ratified by all member States, and there is a strong move afoot in the U.S. to withhold ratification until certain measures have been modified to more properly conform to a private sector exploitation of the space resource.
Military considerations must also be reviewed. Although the SPS does not serve a direct military function, there are potential weapons capabilities which would accommodate SPS power output. The SPS could also be used to relay power to military installations (such as satellites, military aircraft and remote terrestrial stations), or it could function as an observation post for surveillance or some other manned military function. Even if it did not serve in such a capacity, it would make an attractive target and might require some defensive capability. An SPS with offensive or defensive capability would have a negative impact on international relations. Therefore, international agreements will be needed to minimize SPS vulnerability and to ensure the non-militarization of SPS (Bloomquist, l978; Bain, 1978; Ozeroff, 1978).
Public acceptance will be crucial to SPS implementation. The public issues seem to revolve around perceived and real microwave radiation effects, cost, land use/siting and consequences of centralization inherent in the SPS Reference System concept (Bloomquist and colleagues, 1979). Internationally, public acceptance may be less important than government concerns, especially if an initially U.S. SPS organization moves towards international status similar to the COMSAT/INTELSAT relationship.
The least understood area concerns the possible centralizing/decentralizing effects of the SPS. As discussed earlier, there is an increasing trend in the United States towards a decentralized energy policy. This is a “grass roots” tendency and apparently reflects the will of the people. The centralized nature of the SPS Reference System will impact on this basic trend and may generate real public acceptance problems.
Bachrach (1978) identifies the internationalization of the environmental movement with its current opposition to nuclear energy in Europe where the movement has succeeded in causing cutbacks in many government plans to expand nuclear power and with its concern for land use in the battle over the Narita International Airport in Japan. . Whereas the environmental concerns over nuclear energy may work for the implementation of SPS, land use concerns may work against it. It is also possible that the environmental impact of microwave radiation will catch the attention of the same people who so successfully fought the expansion of nuclear energy in Europe.
The environmental impact of the SPS Reference System falls into four areas (U.S. DOE, 1978a):
a. Microwave effects on health and ecology.
b. Non-microwave effects on health and ecology.
c. Effects on the atmosphere.
d. Effects on communications.
The effects of microwaves on health and ecology have been looked at in detail by Newsom (1978) in his exhaustive study on the state of knowledge for electromagnetic absorbed dose in man and animals. However, the fundamental conclusion is that what we know is much less than what we do not know about the subject. There continues to be a need for research in the areas where no data presently exist; especially research on the effects of continuous, low level exposure on humans, and short-term, high-level exposures on airborne biota.
Deployment of an SPS will also generate other health and safety effects. These result from mining of raw materials, construction of terrestrial facilities, processing and fabrication of finished materials, transport of materials and equipment, ground station operation, space vehicle launch and recovery, orbital transfer of material and personnel, construction of SPS arrays, and operation of arrays. These activities will produce effects on the general public, terrestrial workers, space workers, and the environment. They fall into two broad categories. Many of the indicated activities are quite conventional (e.g., mining, construction, processing, transport), and the impacts they produce are common to any use of those processes. The health effects of air pollution generated by steel-making, for example, are the same whether that steel is used for automobiles, bridges, power plants or an SPS. An evaluation of these impacts with respect to the SPS is only significant insofar as SPS deployment results in a substantial increase in a particular activity and its accompanying effects.
The second category results from activities unique to SPS deployment such as the handling of large quantities of gallium arsenide for solar cells and exposure of construction workers to extended periods in the space environment. For activities in this category, data are limited or non-existent, and in some cases, assessment must await the process itself.
Also to be considered are the unconventional effects caused by the potentially large-scale use of toxic materials, by the possibility of transport accidents involving the use of rocket propellants, and by launch and recovery activities resulting in air pollution, water quality impacts, noise, and accidents.
The U.S. DOE (1978a) has already defined environmental loadings which result from material requirements brought about by increased conventional activity. It has addressed the concentration limits for propellants in water and for air pollutants peculiar to SPS deployment and has also addressed the impacts of acoustic noise resulting from launch activities. It has completed a preliminary occupational health and safety analysis for terrestrial workers, and has defined the areas of potential impact on space workers. For terrestrial workers, the major area of impact seems to be material acquisition. For space workers, the major areas under investigation are weightlessness and radiation, which is defined to include cosmic and solar particle radiation, trapped electron and proton effects, magnetic and electric field effects, plasma arcing, and collisions with space debris and meteoroids.
The effects of SPS deployment on the atmosphere can be broken down into two areas, those relating to microwave and rectenna activities, and those relating to launch and transport operations. The possible relationships between rectenna, weather and climate are shown in Fig. 4. Analysis by the U.S. DOE (1978a) shows that rectenna waste heat will produce about the same atmospheric effect as a suburban area and that atmospheric attenuation of the microwave beam will be too small to produce significant meteorological disturbances. However, loss of beam control could have consequences which require further study.
Fig. 4 Climatological and heating effects of the microwave power transmission system in the lower atmosphere.
Between 60 and 500 km, the atmosphere is subject to modification from rocket thruster effluents and from oblation materials generated upon vehicle reentry. The major effects appear to occur in the ionospheric F2 region, resulting primarily in enhanced airglow. While not posing any threat to safety at ground level, it may affect planetside optical sensing devices. Beyond 500 km, the effects are related to heavy ion concentration due to rocket effluents, and to electric and magnetic fields generated by the orbiting SPS. These potential problems are not well understood and require further study. Because of deficiencies in our understanding of the physical and chemical processes above 40 or 50 km, especially with regard to water budget, there is a large uncertainty connected with any prediction. However, climatic effects that may arise from SPS-related perturbations in stratospheric and mesospheric composition are not expected to be highly significant (U.S. DOE, 1978a).
Communications can be affected both directly and indirectly by the SPS Reference System. The harmonics and noise sidebands produced by microwave power transmission have the potential for interfering with SATCOM, microwave links, radar and radio astronomy. It is possible that a permanent degradation in one or more of these areas will be an inevitable consequence of SPS deployment. Although power lost due to scattering of the microwave beam does not appear to have any significant climatic effects, it is sufficient to degrade receivers used for communication, radar and radio astronomy, and might even affect hardwired computer and control systems. The latter can be protected by appropriately designed filter systems, but the former will require an intensive ITU review of frequency allocations and other considerations to minimize the interference effects. As with the direct effects, there may be a residual interference problem which will not go away.
Lasers involve electromagnetic radiation whose wavelength is some 10,000 times shorter than microwaves. Because of this, transmitting and receiving components can be 10,000 times smaller in principle. Translated into real world terms, a transmitter ten meters in diameter in geosynchronous orbit can potentially send laser power at two micrometers wavelength to an earthside collector 40 meters in diameter with better than 90 per cent efficiency averaged over time. Rather (1978) estimates that such a transmitter would weigh 10 tons instead of 30 to 50 kilotons estimated for the equivalent SPS Reference System.
Bain (1978b) has analyzed the effect of laser power transmission from an economic, societal and environmental viewpoint. The results of his study are summarized in Tables 3, 4, and 5.
TABLE 3 Comparison of Economic Effects
TABLE 4 Comparison of Societal Effects
The use of laser power transmission versus microwave power transmission has a dramatic impact on the overall acceptability of the SPS. The economic advantages are tied to the very much smaller satellite required for the laser option and to the correspondingly small rectenna. In Nansen’s and Johnson’s economic analysis (1979) nearly 40 per cent of the total cost was absorbed by the in-space and rectenna structures. This portion of the total cost would be substantially reduced by the laser option. In addition, the smaller production effort should result in less energy being invested, and therefore, in a shorter energy payback time. This could result in an overall savings of one quarter to one-third of the projected per kilowatt cost.
The laser power transmission option also provides a significant reduction in the societal impact of the SPS. Siting considerations are no longer a problem; 40 meter receiving sites appropriately protected by buffer zones can be located almost anywhere within range of the SPS, and practical offshore sites take on real significance as will be discussed later.
All of the environmental and communication problems identified as resulting from the microwave transmission of power go away. While it is true that certain new problems surface, mainly related to the relatively intense heat generated near the concentrated laser beam, these problems seem controllable and do not appear to have any of the potentially far reaching consequences of those related to microwave power transmission. The one exception is the possibility of using the laser option as a weapon, and since the international community is so sensitive to the use of space for military purposes, this problem will require closer study. In conjunction with this, it should be noted that any use of the laser option for weapons purposes would have to be designed into the SPS from the beginning. Since the SPS is an energy system concept that is subject to full disclosure and public participation, any weapon mode designed into the SPS will be subject to public scrutiny.
TABLE 5 Comparison of Environmental Effects
Hydrogen production from power delivered by the SPS must be considered in the light of real world considerations in addition to its application within a total hydrogen economy. Ultimately, an SPS is envisioned which uses a laser tuned to a resonant wavelength of the water molecule for direct production of hydrogen. In the meantime, however, the SPS must be considered basically an electricity producer. Hydrogen should be viewed as an energy carrier for SPS energy under those circumstances where delivery of the energy in electrical form may not be practical. Ideally, the initial receiver sites would be so located that they would efficiently augment the local grid and could gradually take up the slack created by retiring conventional power generators, while at the same time generating hydrogen during grid off-peak periods. This is illustrated in Fig. 5. Figure 6 (Woodcock, 1976) illustrates a typical grid power variation cycle with a level input contributed by an SPS. During those times when grid output falls below the constant SPS input, hydrogen is produced.
Fig. 5. Integrated grid structure.
Fig. 6. SPS and grid power variation.
With the passage of time, more and more of the grid demand will be supplied by SPS as conventional power generators are retired out of the system and new satellites are constructed. There will be a concurrent increase in hydrogen production. Moreover, grid demand itself will increase. However, instead of expanding the grid, this scenario calls for meeting the increased demand with hydrogen energy. This hydrogen would be delivered by tanker and/or pipeline to the area of increased grid demand. Gregory (1973) has shown that the distribution cost of hydrogen per unit of delivered energy is less than one-fourth that of electricity. Furthermore, where the loss of grid capability due to the aging of grid elements and their subsequent retirement from the grid is a factor, the slack can be picked up by extending the hydrogen delivery system rather than by replacing the grid elements. Equilibrium within a balanced energy budget is finally reached when the only remaining grids are those associated with local hydrogen powered electrical generating systems.
A form of deliverable energy thus far not considered in this paper is natural gas. Natural gas is assumed to be a limited commodity. The extensive network of natural gas pipelines and LNG carriers need not fall into disuse with the demise of this commodity. The existent natural gas pipeline network is in many respects ideally suited for the transmission of hydrogen. As natural gas supplies dry up, a gradual conversion of this network to hydrogen use will significantly lower the initial cost of delivering hydrogen from receiver sites to user locations. Relatively minor modifications to LNG carriers make them well suited for liquid hydrogen transport. Use of these carriers would enable the delivery of hydrogen to wherever it can be used.
Looking towards the future, modified LNG carriers, or perhaps specially constructed ships, will enable establishment of remotely located deep ocean rectennas which will remove almost all of the remaining objections to implementation of an SPS. The end result, and the bottom line of this proposal, is abundant, inexpensive, non-polluting, renewable energy for all mankind.
The author wishes to express his gratitude to Hubert P. Davis of Johnson Space Center, NASA, to Gordon R. Woodcock of Boeing, and to Jerald Driggers, President of the L-5 Society, for their invaluable advice in the preparation of this paper. Recognition is due the staff of NASA’s Technical Library, Langley, for their kind assistance and to David Butler of the Atlantic Marine Center for his artistic contributions. Thanks are also due Jean Martin, Carol Birch, and Jeanette Bass of the Atlantic Marine Center, without whose administrative assistance the publishing deadline for this paper could not have been met.
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